[N] 2006 Digesting the Coelophysis-cannibal hypothesis
Nesbitt, S., Turner, A. & Erickson, G. (2006) Digesting the Coelophysis-cannibal hypothesis and its importance to prey choice in Theropod dinosaurs. JVP 26(3) Abstracts pp.105
Direct evidence of prey choice in carnivorous dinosaurs is rare in the fossil record. The most celebrated example pertains to purported stomach contents in two specimens of the early carnivorous dinosaur Coelophysis bauri (AMNH FR 7223 and AMNH FR 7224), which besides revealing prey choice, also point to cannibalistic behavior as being commonplace among theropod dinosaurs. The Coelophysis-cannibal hypothesis is one of the most recognized paleobiological anecdotes presented in museum exhibitions, countless children’s books, and in popular press. Here, we test this hypothesis by conducting the first comprehensive anatomical and histological examination of the famed Coelophysis cannibals.
Reinspection of AMNH FR 7223 revealed that the ribcage ruptured sometime during burial and that the purported remains lie underneath the Coelophysis skeleton. Thus, no unambiguous stomach contents are present in AMNH FR 7223. The stomach remains in AMNH 7224 lie within the posterior region of the intact ribcage. The stomach contents include an ilium, left and right femora, a sacral vertebra, and many additional fragments. None of the stomach remains bear dinosaurian synapomorphies. Instead, the elements bear character states consistent with crocodylomorph archosaurs. The preserved femur has a proximal condylar fold, which is synapomorphic for Crocodylomorpha. Morever, histological analysis of the femur supports assignment to Crocodylomorpha rather than a Theropoda.
The results unequivocally show that the gut contents derive from early crocodylomorphs rather than juveniles of Coelophysis. These findings exonerate this taxon as being cannibalistic and bring into question the commonality of this behavior among non-avian dinosaurs.
Direct evidence of prey choice in carnivorous dinosaurs is rare in the fossil record. The most celebrated example pertains to purported stomach contents in two specimens of the early carnivorous dinosaur Coelophysis bauri (AMNH FR 7223 and AMNH FR 7224), which besides revealing prey choice, also point to cannibalistic behavior as being commonplace among theropod dinosaurs. The Coelophysis-cannibal hypothesis is one of the most recognized paleobiological anecdotes presented in museum exhibitions, countless children’s books, and in popular press. Here, we test this hypothesis by conducting the first comprehensive anatomical and histological examination of the famed Coelophysis cannibals.
Reinspection of AMNH FR 7223 revealed that the ribcage ruptured sometime during burial and that the purported remains lie underneath the Coelophysis skeleton. Thus, no unambiguous stomach contents are present in AMNH FR 7223. The stomach remains in AMNH 7224 lie within the posterior region of the intact ribcage. The stomach contents include an ilium, left and right femora, a sacral vertebra, and many additional fragments. None of the stomach remains bear dinosaurian synapomorphies. Instead, the elements bear character states consistent with crocodylomorph archosaurs. The preserved femur has a proximal condylar fold, which is synapomorphic for Crocodylomorpha. Morever, histological analysis of the femur supports assignment to Crocodylomorpha rather than a Theropoda.
The results unequivocally show that the gut contents derive from early crocodylomorphs rather than juveniles of Coelophysis. These findings exonerate this taxon as being cannibalistic and bring into question the commonality of this behavior among non-avian dinosaurs.